Preheat oven to 350 degrees F.
Season the fish with the salt and pepper. Spread the onions and peppers in a 9x13 glass baking dish and place the fish on top. Dot the fish with butter. Sprinkle with Worcestershire sauce.
Bake for 12 minutes. Baste fish with pan juices. Sprinkle the fish with Parmesan and then place under the broiler for about 2 minutes or until the cheese browns. To serve, spoon the vegetables over the fish.